The 2M1-phlogopite from the potassic gabbronorite (Black Hill, Australia) has been studied by electron microprobe and single-crystal X‑ray diffraction analyses. The crystal-chemical formula was (K0.95Na0.01)(Al0.15Mg1.27Fe2+1.16Fe3+0.04Ti4+0.38)(Si2.85Al1.15)O10.76F0.11Cl0.03OH1.10. The structural analysis has shown that the crystal has the cell parameters a = 5.352(1), b = 9.268(1), c = 20.168(1) Å, and β = 95.10(1)° and exhibits symmetry lowering from the ideal space group C2/c to C1. An octahedral cation ordering pattern was revealed from the refined site-scattering powers. Specifically, using the scattering species Mg vs. Fe, it was found that the M1 site at z = 0 was occupied principally by Mg (~77%) and subordinately by Fe (~23%), whereas that at z = 0.5 was completely occupied by Fe; the M2 sites at z = 0 displayed ~88% Mg and ~12% Fe, whereas those at z = 0.5 were occupied by ~86% Fe and ~14% Mg. The analysis of geometrical features shows that the Ti uptake in the structure via the Ti-oxy mechanism induces structural distortions of different extents on the z = 0 and z = 0.5 layers, with stronger effects for the layer at z = 0. Minor chemical and structural differences, instead, affect the T sheets at z = 0 and z = 0.5.

3T trioctahedral micas are rarer than it is thought. This is likely due to the occurrence of apparent polytypism, so that 1M polytype twins result in a diffraction pattern simulating a 3T periodicity [1, 2]. Most of the 3T trioctahedral micas found in nature to date belong to muscovite-polylithionite-annite system [3, 4, 5, 6]. X-ray diffraction studies on these micas have often reported partial tetrahedral ordering and/or different patterns of octahedral ordering [3, 6]. In the present work, a 3 T trioctahedral mica from Kasenyi (south west Uganda) kamafugite was studied via Electron Probe Microanalysis (EPMA) and Single Crystal X-ray Diffraction (SCXRD). Main EPMA data gave: SiO2 = 38.7(2), Al2O3 = 13.08(9), MgO = 20.4(2), TiO2 = 4.8(1), FeOtot = 5.51(9), Cr2O3 = 0.90(7), K2O = 9.64(5), Na2O = 0.29(1), BaO = 0.15(5) and F = 0.13(5) wt%. The analysed crystal may be classified as a Ti-rich, F-poor mica with a composition intermediate between the annite and phlogopite end members. Anisotropic single crystal X-ray refinement was performed in the <i>P</i>3<sub>1</sub>12 space group and converged to R1 = 4.34 and wR2 = 3.33 %. Unit cell parameters were: a = b = 5.3235(3) and c = 30.188(2) Å. Mean bond length distances of M1, M2 and M3 follow the pattern M1 = M2 < M3, suggesting partial octahedral cation ordering. Conversely, mean bond lengths of T1 and T2 point to a disordered cation distribution over tetrahedral sites. Finally, the overall crystal chemical features indicates the occurrence in the studied sample of the following substitution mechanisms: tetraferriphlogopite; Ti-oxy and Al, Fe3+, Cr-oxy; Al, Fe3+-Tschermak; kinoshitalite and XIIK+ + IVAl3+ « IVSi4+ + XII. Such substitutions are the same as those found in 1M-2M1 coexisting micas from the same rock sample [7].

A 3T mica polytype from Kasenyi (south west Uganda) kamafugite was studied by Electron Probe Microanalysis (EPMA), Single Crystal X-ray Diffraction (SCXRD), micro-Fourier Transform Infrared Spectoscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) in order to characterize its crystal chemistry and the relationships with samples from the same rock but showing different stacking sequence. EPMA data gave: SiO2 = 38.7(2), Al2O3 = 13.08(9), MgO = 20.4(2), TiO2 = 4.8(1), MnO = 0.03(3), FeOtot = 5.51(9), Cr2O3 = 0.90(7), NiO = 0.11(5), SrO = 0.03(3), ZnO = 0.04(3), ZrO2 = 0.01(2), K2O = 9.64(5), Na2O = 0.29(1), BaO = 0.15(5), F = 0.13(5) and Cl = 0.01(1) wt%. The analysed sample may be classified as a Ti-rich, F-poor mica with a composition in the phlogopite- annite join end members. X-ray photoelectron spectroscopy provided Fe2+/Fe3+ and O2- /OH equal to ~ 0.75 and 7.14, respectively, which are in agreement with the results of previous Mössbauer investigation on the BU1 sample and with the structural formula of the studied crystal. Infrared spectra showed, in the OH- stretching region (~ 3740-3600 cm-1 cm-1), a shoulder at ~ 3660 cm-1 which is assigned to MgMgFe3+-OH--K-O2- local configurations. No evidences of vacancy substitutions were observed. Single crystal X-ray refinement using anisotropic displacement parameters was performed in the P3112 space group and converged to R1 = 4.34 and wR2 = 3.33 %. Unit cell parameters are: a = b = 5.3235(3) and c = 30.188(2) Å. Geometrical and chemical considerations point to a disordered cation distribution over T1 and T2 tetrahedral sites, whereas partial cation ordering characterizes the octahedral sites with M1 = M2 ≠ M3. Tetrahedral bond/edge lengths distortion and angle variances parameters evidence more distorted polyhedra in 3T polytype than those found in coexisting 1M and 2M1 polytypes. Finally, the overall crystal chemical features indicates the occurrence in the studied sample of the following substitution mechanisms: tetraferriphlogopite [IVFe3+ IVAl]; Ti-oxy [VIM2+ + 2 (OH)  VITi4+ + 2 (O2–) + H2] and Al, Fe3+, Cr-oxy [VIM2+ + (OH)  VIM3+ + O2– + ½ (H2)]; Al, Fe3+-Tschermak [VIM2+ + IVSi4+  VI(Al3+, Fe3+) + IVAl3+]; XIIK+ + IVAl3+  IVSi4+ + XII.

Muscovite, KAl2[AlSi3O10](OH)2, is a common rock-forming mineral in igneous and metamorphic-rocks, sediments, hydrothermal alteration and ore deposits. The site between two adjacent T-O-T (tetrahedral-octahedral-tetrahedral) layers is shared between K and NH4 in any proportion leading to the building of the “ammonium micas”. Mica with: (i) NH4>K, □ (vacancy); (ii) Si ≥ 3 apfu (atoms per formula unit); (iii) layer charge (T-O-T) less than one, is named tobelite [Brigatti M F and Guggenheim S 2002 Rev. Mineral. Geochem. 46 1-97]. The NH4-analog of muscovite, i.e., tobelite, has been predominantly associated to two distinct geological settings: a) diagenetic to low grade metamorphic shales from meta- anthracite and anthracite coal fields; b) hydrothermal areas alteration [Ruiz Cruz M D and Sanz de Galdeano C 2010 Clays Clay Miner. 58 558-572]. In this work three crystals labelled Tob_M2, Tob_M3, Tob_3 were investigated by electron probe microanalysis (EPMA) in terms of major constituents, and in terms of nitrogen by secondary ion mass spectrometry (SIMS) in order to gain information on the presence and amount of NH4. Nitrogen was detected as secondary positive ions by means of a Cameca IMS 4f ion microprobe installed at CNR-IGG, Pavia. SIMS analysis on 14N+ was performed with 16O- primary beam at a mass resolution (M/ΔM) of ~ 1250 required to discriminate the 28Si2+ and 12CH2 + interferences at the nominal mass number 14 (a.m.u.). In spite of the severe inhomogeneity of nitrogen in each crystal, the SIMS data put Tob_M2 as the N-richest crystal of the set. The crystal, analyzed at different spots, is characterized by an ion signal in the range 399 - 560 (c/s). For Tob_M3 the 14N+ average ion signal is 91 (c/s). In Tob_3 the N content is likely the lowest in the sample set with an average count rate of 61 (c/s). The lack of calibration standards did not allow so far to obtain quantitative results for N at the ion microprobe. Nevertheless, our SIMS data agree qualitatively with constraints derived from EPMA and charge-balance crystal chemical considerations, and point out that the ion probe is a valuable tool for the investigation of N in mica minerals.

The results of a combined electron probe microanalysis, single-crystal X‑ray diffraction, and Fourier transform infrared study of a crystal of armstrongite from Khan Bogdo deposit (Gobi, Mongolia) are reported. Major element analysis provided (wt%): CaO 9.2(1), ZrO2 20.9(2), and SiO2 62.5(2). Significant concentrations of REE (0.45 wt%) were also detected. From single-crystal structural refinement, armstrongite resulted monoclinic [space group C2/m, a = 14.0178(7), b = 14.1289(6), c = 7.8366(3) Å, b = 109.436(3)°, V = 1463.6(1) Å3, Z = 4] and twinned with two individuals rotated around a twin twofold axis parallel to [100]. The analyzed crystal was refined up to R = 3.3% (Rw = 2.9%). The structural refinement showed that the investigated armstrongite has only two water groups per formula unit consistent with the infrared analysis. Indeed, the occurrence in the infrared spectrum of the armstrongite (here reported for the first time) of two bending vibration bands at about 1640 and 1610 cm–1 testifies to the presence of two water groups environments. The results of this integrated approach converged to the following empirical formula (based on Si = 6 atoms per formula unit): (Ca0.96Ce0.01Yb0.01)Zr0.99Si6O14.97·2.02H2O. Finally, the studied mineral shows a framework density (FD = 21.86) lying in the range of zeolites and microporous heterosilicates with tetrahedral-octahedral frameworks. The determined crystal chemical features are relevant for the possible employment of this mineral or of its synthetic analogs for technological applications.

Gold nanoparticles stabilized on metal oxide supports have found a wide range of applications especially in heterogeneous catalysis and gas sensing. A facile methodology for the in situ electrodecoration of gold nanoparticles on metal oxide supports is presented herein. Metal oxides such as indium oxide (In2O3) and zirconia (ZrO2) nanoparticles are first prepared via the sol-gel route. Subsequently, gold nanoparticles are electrodeposited in situ on the surface of these metal oxides using a modified sacrificial Au-anode electrolysis procedure. Both pristine as well as electrodecorated metal oxides are characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM, TEM). SEM images of electrodecorated metal oxides reveal successful deposition of gold nanoparticles on metal oxide supports. XPS shows that nano-sized gold is significantly available on the materials' surface and it is in the elemental oxidation state. Moreover, it is found that the electrodecoration of gold nanoparticles on metal oxide surfaces proceeds as a function of the concentration of hydroxyl groups on the surface of metal oxide supports.

Very high temperature, Ca-rich alkaline magma intruded an argillite formation at Colle Fabbri, Central Italy, producing cordierite-tridymite metamorphism in the country rocks. An intense Ba-rich sulphate-carbonate-alkaline hydrothermal plume produced a zone of mineralization several meters thick around the igneous body. Reaction of hydrothermal fluids with country rocks formed calcium-silicate-hydrate (CSH), i.e., tobermorite-afwillite-jennite; calcium-aluminum-silicate-hydrate (CASH) — “cement” phases - i.e., thaumasite, strätlingite and an ettringite-like phase and several different species of zeolites: chabazite-Ca, willhendersonite, gismon-dine, three phases bearing Ca with the same or perhaps lower symmetry of phillipsite-Ca, levyne-Ca and the Ca-rich analogue of merlinoite. In addition, apophyllite-(KF) and/or apophyllite-(KOH), Ca−Ba-carbonates, portlandite and sulphates were present. A new polymorph from the pyrrhotite group, containing three layers of sphalerite-type structure in the unit cell, is reported for the first time. Such a complex association is unique. Most of these minerals are specifically related to hydration processes of: (1) pyrometamorphic metacarbonate/metapelitic rocks (natural analogues of cement clinkers); (2) mineralization between intrusive stocks and slates; and (3) high-calcium, alkaline igneous rocks such as melilitites and foidites as well as carbonatites. The Colle Fabbri outcrop offers an opportunity to study in situ complex crystalline overgrowth and specific crystal chemistry in mineral phases formed in igneous to hydrothermal conditions.

Abstract In the present work, crystal chemical variations between 1M and 2M1 phlogopites coexisting in the same rock sample from kamafugite of Kasenyi (southwest Uganda, west branch of the East African Rift) were explored by electron probe microanalyses, single crystal X-ray diffraction and Mo¨ ssbauer spectroscopy. Chemical analyses revealed close similarity both within and between the two polytypic arrangements as well as high TiO2 (*4.9 wt%) and Al2O3 (*12.9 wt%), and low Cr2O3 (*0.8 wt%), F (*0.3 wt%) and BaO (*0.2 wt%) con- tents. Room temperature 57Fe Mo¨ ssbauer investigation proved that the studied mica is a tetraferriphlogopite with: IVFe3? = 19(1) %, VIFe2? = 58(1) %, VIFe3? = 23(1) %. Single crystal refinement showed that both polytypes have narrow range of variation in terms of some relevant unit cell parameters and similar values in terms of mean bond lengths, mean atomic numbers and distortion parameters. Similar substitutions were active in the structure of the 1M and 2M1 studied phlogopites. However, in 2M1 poly- types the oxy-type substitutions were found to occur to a greater extent. Comparison of unit layer of 1M mica (in the 2M1 setting) with that of the 2M1 ones showed that the 2M1 polytypes are affected to different extent by relative shifts of the upper and lower triads of octahedral oxygens along the ±b directions. This effect did not cause any symmetry lowering in the T-O-T layer of the studied samples.

In the present work, the crystal chemistry of natural Tiphlogopites from alkali-rich igneous rocks from the Central Fields of Bunyaruguru and Katwe-kikorongo (Southwest Uganda) has been investigated. The host rocks are characterized by olivine – melilitite and olivine – kalsilite – nepheline – clinopyroxene assemblages [1]. The phlogopites from the former rock are labelled BU (specifically, BU1, BU3 and BU4) whereas those from the latter are labelled KK (in detail, KK8 and KK13). All samples underwent chemical (Electron Micro Probe Analysis, EMPA), structural (Single Crystal X-ray Diffraction, SCXRD) and spectroscopic (FTIR) investigation. EMPA yielded the following ranges: MgO (17.87-21.48 wt%), FeOtot (5.40-9.22 wt%) and TiO2 (4.59-7.05 wt%) for BU samples whereas MgO (17.98-18.51 wt%), FeOtot (8.17-8.86 wt%) and TiO2 (6.02-6.49 wt%) for KK crystals. SCXRD analyses showed the coexistence of both the 1M and the 2M1 polytypes within the same sample. The BU3 mica is an exception because, to date, only crystals belonging to the 2M1 polytype have been found. Average cell parameters are a = 5.33, b = 9.22, c = 10.22 Å and = 100.06° for the 1M whereas a = 5.33, b = 9.23, c = 20.22 Å and = 95.08° for the 2M1 phlogopites. Structure refinements using anisotropic displacement parameters were performed in space group C2/m for 1M and C2/c for 2M1 samples and converged at 1.63 R 4.64 %, 1.96 Rw R Rw 4.41 % for the two polytypes, respectively. Micro-FTIR provides insightful informations about octahedral cationic environments, the substitution mechanisms trough which cations enter the mica structure and the hydrogen orientation [2-4]. The samples so far analyzed display, to different extent, fine structure in the OH- stretching region. In terms of substitution mechanisms this implies that the samples contain different combination of M3+-Tschermak, M3+- oxy substitutions, whereas they are not affected by M3+-vacancy substitutions. Indeed the bands at about 3620 and 3535 cm-1, which correspond to Al3+Al3+-OH and Fe3

The crystal chemistry of 2M1 micas from Bunyaruguru kamafugite (southwest Uganda) was studied by electron probe microanalysis, single-crystal X-ray diffraction, Mössbauer and Fourier transform infrared spectroscopy. Chemical analyses showed that the studied crystals are Ti-rich, F-poor phlogopites with an annitic component, Fetot/(Fetot + Mg), ranging from 0.15 to 0.22. Unit-cell parameters from single-crystal X-ray data are in the range: 5.3252(1) ≤ a ≤ 5.3307(1), 9.2231(3) ≤ b ≤ 9.2315(3), 20.1550(6) ≤ c ≤ 20.1964(8) Å, and 94.994(2) ≤ β ≤ 95.131(2)°. Anisotropic structure refinements, in the space group C2/c, converged to 2.77 ≤ R1 ≤ 3.52% and 2.91 ≤ wR2 ≤ 4.02%. Mössbauer spectroscopy showed that the studied sample has: VIFe2+ = 60(1)%, VIFe3+ = 24(1)%, and IVFe3+ = 16(1)%. FTIR investigations pointed to the occurrence of Fe3+-oxy substitutions and ruled out the presence of vacancy mechanisms. The overall crystal-chemical features are consistent with the following substitutions: tetraferriphlogopite [IVFe3+ ↔ IVAl]; Ti-oxy [VIM2+ + 2 (OH)− ↔ VITi4+ + 2 (O2−) + H2↑] and Al, Fe3+, Cr-oxy [VIM2+ + (OH) − ↔ VIM3+ + O2− + ½ (H2)↑]; Al, Fe3+-Tschermak [VIM2+ + IVSi4+ ↔ VIM3+ + IVAl]; kinoshitalite [XIIK + IVSi4+ ↔ XIIBa2+ + IVAl] and [XIIK+ + IVAl3+ ↔ IVSi4+ + XII□]. The estimation of the OH− content for Ugandan mica-2M1 was obtained, for the first time, from the linear regression equation c = 0.20(2) × OH− (gpfu) + 19.93(2) derived from literature data of 2M1-samples with known OH− content. The orientation of the O-H vector with respect to c* was found in the range from 2.0 to 6.9°.

In trioctahedral micas, polytype 2 M1 occurs less frequently than 1M one. For such a reason, trioctahedral 1M-polytype has been extensively studied up to date whereas studies on 2 M1-polytype are relatively rare. In several cases 2 M1-micas have been reported as coexisting with 1M-micas [1, 2, 3, 4, 5]. Other studies were focused on the characterization of phlogopite-annite 2 M1 micas with peculiar composition [6, 7, 8, 9, 10]. The crystal chemistry of 2 M1 micas from Bunyaruguru (south west Uganda) kamafugite was studied by Electron Probe Microanalysis, Single Crystal X-ray Diffraction, Mössbauer and Fourier Transform Infrared spectroscopy. To the best of our knowledge, this is the first integrated crystal chemical study of phlogopite from Ugandan kamafugites, and was undertaken to get an insight into the crystal chemistry of the trioctahedral mica 2 M1-polytype. Chemical analyses showed that the studied crystals are Ti-rich, F-poor phlogopites with an annitic component, Fe<sub>tot</sub>/(Fe<sub>tot</sub> + Mg), ranging from 0.15 to 0.23. Unit-cell parameters from single crystal X-ray data are in the range: 5.3252(1) < a ≤ 5.3307(1), 9.2231(3) < b ≤ 9.2315(3), 20.1550(6) < c < 20.1964(8) Å and 94.994(2) < β ≤ 95.131(2)°. Anisotropic structure refinements, in the space group C2/c, converged to 2.80 < R1 ≤ 3.56 % and 2.91 < wR2 ≤ 4.08 %. Mössbauer spectroscopy showed that the studied sample has: VIFe2+ = 60(1) % , VIFe3+ = 24(1) % and IVFe3+ = 16(1) %. FTIR investigations pointed to the occurrence of Fe3+-oxy substitutions and ruled out the presence of vacancy mechanisms. The overall crystal chemical features are consistent with the following substitutions: tetraferriphlogopite; Ti-oxy and Al, Fe3+, Cr-oxy; Al, Fe3+-Tschermak; kinoshitalite and XIIK+ + IVAl3+  IVSi4+ + XII. The estimation of the OH<sup>-</sup> content for Ugandan mica-2 M1 was obtained, for the first time, from the linear regression equation c = 0.20(2) x OH- (gpfu) + 19.93(2) derived from literature data of 2 M1-samples with known OH- content. The orientation of the O-H vector with respect to c* was found in the range from 2.8 to 12.6°, consistently with literature values [11].

Tinaksite from ultralkaline agpaitic Murun massif (Russia) has been investigated. The name reflects its composition: titanium (Ti), sodium (Na), potassium (K) and silicon (Si). Its structure was reported for the first time in 1971 by Petrunina [1]. To the best of author's knowledge, tinaksite is the only silicate based on {hB, 21 }[3Si6O17(SiO2)] hybrid anion [2]. The structural model of Tinaksite proposed by Petrunina [1] was validated and improved by von Bissert [3] in 1980, who observed a more regular tetrahedra conformation. The tinaksite investigated by von Bissert [3] is triclinic with chemical composition: NaK2Ca2Ti[3Si7O19]OH. The compound here investigated has chemistry more complex, ((Na0.855K1.993Ca 2.008Ti0.792Mg0.083Fe3+0.096Mn0.100Zr0.027Sr0.013Zr0.027Zn0.008Ni0.007Cr0.005)[3Si7O19]OH), compared with Petrunina's [1] and von Bissert's [3] ones. It has been refined in P1, using the following lattice parameters: a = 7.0565(1) Å, b = 10.3750(1) Å, c = 12.1885(2) Å, = 92.802(1)°, = 90.763(1)°, = 99.241(1)°. In this work, the cation partition derived from SCXRD and EPMA data, is presented. The structure has been anisotropically refined up to an R(F) = 0.025 (for 5238 observed reflections with Fo > (Fo)). Tinaksite exhibits straight channels parallel to [001] direction, formed by double chains of silicate. The channels are stretched approximately along [110] direction, with maximum dimension 10.972(2) Å. The highest peak in the Fourier difference map is related to some structural disorder inside the Ti octahedron. This disorder likely can be ascribed to the entrance of the large K substituting the six-fold coordinated Na atom. As a matter of fact, the replacing of Na for K changes the coordination number of the polyhedron from 6 to 7, which seems to influence the neighbouring Ti atom position. Another point concerns the K1 and K2 atoms located inside the channels. According to von Bissert [3], the higher K1 thermal parameter with respect to the K2 one indicates the site filled by K1 is disorder. The structural refinement shows that K1 atom is located over at least three different positions. A charge distribution analysis, performed by means of the Chardi-It software [4], has returned an ECON number [5] of 11 and 9 for the K1 and K2, respectively. The bond distances for the three K atoms, related to K1, show these atoms are not always bonded to the same oxygens. Indeed, K1 can move inside a cage formed by 14 oxygen atoms with a volume of about 90 Å3. This volume results to be much larger even than the one of the ideal twelve-fold coordinated K atom (~18 Å3).

The aim of this work is to investigate the efficiency of the phyllomanganate birnessite in degrading catechol after mechanochemical treatments. A synthesized birnessite and the organic molecule were grounded together in a high energy mill and the xenobiotic-mineral surface reactions induced by the grinding treatment have been investigated by means of X-ray powder diffraction, X-ray fluorescence, thermal analysis and spectroscopic techniques as well as high-performance liquid chromatography and voltammetric techniques. If compared to the simple contact between the birnessite and the organic molecule, mechanochemical treatments have revealed to be highly efficient in degrading catechol molecules, in terms both of time and extent. Due to the two phenolic groups of catechol and the small steric hindrance of the molecule, the extent of the mechanochemically induced degradation of catechol onto birnessite surfaces is quite high. The degradation mechanism mainly occurs via a redox reaction. It implies the formation of a surface bidentate inner-sphere complex between the phenolic group of the organic molecules and the Mn(IV) from the birnessite structure. Structural changes occur on the MnO6 layers of birnessite as due to the mechanically induced surface reactions: reduction of Mn(IV), consequent formation of Mn(III) and new vacancies, and free Mn2+ ions production.

The existence of a lot of worldwide pentachlorophenol-contaminated sites has induced scientists to concentrate their effort in finding ways to degrade it. Therefore, an effective tool to decompose it from soil mixtures is needed. In this work the efficiency of the phyllomanganate birnessite (KBi) in degrading pentachlorophenol (PCP) through mechanochemical treatments was investigated. To this purpose, a synthesized birnessite and the pollutant were ground together in a high energy mill. The ground KBi-PCP mixtures and the liquid extracts were analyzed to demonstrate that mechanochemical treatments are more efficient in removing PCP than a simple contact between the synthesized birnessite and the pollutant, both in terms of time and extent. The mechanochemically induced PCP degradation mainly occurs through the formation of a surface monodentate inner-sphere complex between the phenolic group of the organic molecules and the structural Mn(IV). This is indicated by the changes induced in birnessite MnO6 layers as a consequence of the prolonged milling with the pollutant. This mechanism includes the Mn(IV) reduction, the consequent formation of Mn(III) and new vacancies, and free Mn2+ ions release. The PCP degradation extent is limited by the presence of chloro-substituents on the aromatic ring.

Several diffraction studies on coexisting 1M and 2M1 polytypes have been carried out to date [1, 2, 3, 4, 5, 6] in order to draw informations on their differences by comparing unit layer structure and/or the crystal chemical details of the two polytypic forms. Some of the quoted studies contain implications on polytype formation in micas [1, 2]. In the present work, the crystal chemistry of 1M and coexisting 2M1 micas from Kasenyi (south west Uganda) kamafugite was investigated by Electron Probe Microanalysis, Single C rystal X-ray Diffraction and Mössbauer spectroscopy. The aim of the present study is to compare crystal chemical and unit layer structural features of the coexisting polytypic forms and to make comparisons to literature data. EPMA investigation yielded similar composition for 1M and 2M1 polytypes. They are Ti-rich, F-poor phlogopites with an annitic component, Fetot/(Fetot + Mg), of about 0.14. The room temperature Mössbauer spectrum of the sample yielded three Fe-species: V I Fe2 + = 58(1) % , V I Fe3 + = 23(1) % and I V Fe3 + = 19(1) %. A typical crystal chemical formula is: (K0 .9 6 Na0 .0 4 Ba0 .0 1 )(Mg2 .2 9 Al0 .0 9 Fe2 + 0 .2 1 Fe3 + 0 .0 8 Ti0 .2 8 C r0 .0 4 Ni0 .0 1 )(Si2 .8 7 Al1 .0 6 Fe3 + 0 .0 7 )O1 0 .6 5 F0 .0 5 OH1 .3 0 . Average cell parameters are a = 5.326, b = 9.224, c = 10.231 Å, β = 100.06° for polytype 1M and a = 5.325, b = 9.223, c = 20.206 Å, β = 95.08° for polytype 2M1 . The interatomic distances are similar for the two polytypes and consistent with the relevant site chemistry. The comparison among atomic coordinates of 1M and 2M1 micas from this study and from the literature in the 2M1 setting evidenced a remarkable agreement between all atomic coordinates, with the exception of the y values of the octahedral oxygen atoms. Specifically, the difference between y values was 0.004 in the study samples, 50 times the estimated standard deviations. Similar differences were found for the literature data [1].

Tinaksite is a widespread mineral in the rocks of charoite complex of the Murun massif (Russia). The structure of tinaksite was reported for the first time in 1971 by Petranunia [1]. Until now, it is the only one silicate known based on a hybrid anion. According to Libeau [2], the latter can be described briefly by {hB, 21 }[3Si6O17(SiO2)], which represents the joint of an unbranched dreier single chain with a loopbranched dreier single chain. In 1980 von Bissert [3] confirmed the general structure architecture of tinaksite proposed by Petranunia [1], but found a more regular tetrahedral conformation. According to von Bissert [3], tinaksite is triclinic with the following chemical composition: NaK2Ca2Ti [3Si7O19]OH. The compound here investigated has been solved in P1, a=7.0565(1) Å, b=10.3750(1) Å, c=12.1885(2) Å, 92.802(1)°, , but differently from those studied by Petranunia [1] and von Bissert [3], it shows a more complex chemistry ((Na0.855K1.993Ca2.008Ti0.792 Mg0.082Fe3+ 0.142Mn0.100Ba0.006Sr0.006Zr0.007Zn0.004Ni0.003Cr0.002) [3Si7 O19]OH) and a more interesting structural details. In this work, the cation partition, derived by means of SCXRD and EMPA measurements, is presented. The structure has been anisotropically refined to a R(F) = 0.025 (for 5238 observed reflections with Fo > 3(Fo)). The highest peak in the Fourier difference map seems due to some structural disorder inside the Ti octahedron. This disorder likely is related to the entrance of the large K in place of six-fold coordinated Na atom. The replacing of Na by K seems to change the coordination number of the polyhedron from 6 to 7, so perturbing the neighbouring Ti atom position. Another point of interest concerns the K1 and K2 potassium atom located inside the system of one-dimensional channels of the structure, formed by double chains of silicate. According to von Bissert [3], the higher K1 thermal parameters with respect to the K2 one indicates the disorder on K1 site. The structural refinement shows that in the first case K occupies at least three different positions. A charge distribution analysis, performed by means of the Chardi-It software [4], has returned an ECON number [5] of 11 and 9 for the K1 and K2 site respectively. The bond distances for the three K atoms concerning K1 show these atoms are not always bonded to the same oxygens. In fact, K can move inside a cage formed by 14 oxygen atoms with a volume of about 90 Å3. This volume results to be much larger than of one assigned to K atom.

Possibility to develope reference materials (standards) for quantitative SIMS analysis of nitrogen in mica.

A crystal chemical study of narsarsukite from the Murun alkaline massif, Russia has been carried out combining single crystal X-ray diffraction, electron microprobe analyses, micro-Fourier Transform infrared spectroscopy and X-ray photoelectron spectroscopy. The narsarsukite single crystals are tetragonal (space group I4/m) with unit cell parameters: 10.7140(1)  a  10.7183(2) Å and 7.9478(1)  c  7.9511(1) Å. The XPS analysis showed that Fe occurs in the mineral as Fe3+, whereas the FTIR spectrum evidenced that the studied sample is anhydrous. The Murun narsarsukite has average crystal chemical formula: Na2.04K0.01(V5+0.01Ti0.74Zr0.01Al0.01Fe3+0.22Mg0.01)1.00Si4.00(O10.74F0.23OH0.03) 11.00. Structural disorder at octahedral and interstitial sites was modeled and discussed also in consideration of the main substitutional mechanism Ti4+ + O2- ⟷ Fe3+ + (F-, OH-) active in the structure of the mineral.

The on–board quantification of exhaust emission from the internal combustion engines is of global concern in order to monitor and control release of toxic gaseous pollutants such as the oxides of nitrogen (NOx). This scenario calls for highly performing, cost–effective and long lasting gas sensors. In this regard, semiconducting metal oxides present the foremost choice of active materials for real–time detection of exhaust gases due to their low cost, good electrical properties, high sensitivity and stability at temperatures as high as >500°C [1]. In this work, we report on the synthesis, analytical characterization, and surface modification of metal oxide nanoparticles (ZnO–, ZrOx, InOx- NPs) for their potential application as semiconductor gas sensors. ZnO is a promising material and one of the earliest oxides studied for gas adsorption [2]. However, owing to its high working temperature and limited selectivity, ZnO did not achieve commercial success. ZrOx and InOx nanomaterials are well known active components of NOx sensors, which have shown some performance limitations –either in selectivity or in response intensity and kinetics-. To overcome these limitations, in recent years semiconductor metal oxides (MO) are being frequently modified by selected inclusions of transition metal nanoparticles, bringing their own surface reactivity characteristics to the hybrid catalyst-MO system [3]. In the present study, MO–NPs are prepared via simple and economical sol–gel methods. The surface of MO–NPs is subsequently modified by electro–chemical decoration of nanoscale gold (nano–Au), performed under surfactant stabilization conditions. Since Au nanoparticles exhibit pronounced selectivity toward NOx gases [4], the nano–Au/MO–NPs hybrids are believed to enhance the sensing properties of MO–NPs such as the selectivity and long–term stability of the nanomaterial. Both the pristine MO–NPs and the composite nano–Au/MO–NPs are calcined at temperatures >500°C to induce stability at the usual operating temperature of gas-sensing experiments and the effect of calcination on nanostructure and morphology is systematically studied. The as–prepared and the calcined nanomaterials are characterized by transmission electron microscopy, scanning electron microscopy, X–ray photoelectron spectroscopy, and X–ray diffraction techniques. The results demonstrate that these nanomaterials are highly stable and even ultrafine gold nanophases retain their morphology and surface chemical speciation upon annealing. The experimental evidences support further application of these composite nano–Au/MO–NPs as active elements in semiconductor NOx gas sensors.

Tokkiote is a new mineral discovered in 1986 by Lazebnik et al. [1] on Murun massif (Russia). It belongs to group of alkali-calcium silicates containing hydroxyl and fluorine anions. The SCXRD investigation on this mineral dates back to 1989 [2]. Tokkoite is triclinic with general formula K2a4(Si7O18)(OH,F)2 [2] and is a Ca-bearing compound isostructural to tinaksite [3]; both minerals contain the rare [Si7O18(OH)]9- silicate radical. In this work a re-appraisal of tokkoite structure was undertaken and a cation partition, obtained by means of SCXRD and EPMA measurements, is derived. The structure has been refined in space group P1 (R1 = 4.45%), using the following lattice parameters: a = 10.4222(5) Å, b = 12.5023(6) Å, c = 7.1146(3) Å, = 89.904(2)°, = 99.714(2)°, = 92.979(2)°. The structure consists of layers of calcium octahedra interconnected along (100), between which the silicate-oxygen chains are located. K atoms are located inside the curved shape channels formed by silicon chains. Structural refinement showed that Si-tetrahedra are slightly distorted, but more regular if compared to [2]. Ca(1), Ca(3) and Ca(4) are octahedrally coordinated and appear more distorted than [2], with <Ca(1)-O> = 2.199, <Ca(3)-O> = 2.368, <Ca(4)-O> = 2.371, while in Ca(2) polyhedron Ca-ion seems to be bond to seven oxygen with <Ca(2)-O> = 2.860 Å. The highest peak (3.56 e/Å3) in the Fourier difference map is related to structural disorder at the Ca(1) octahedron, which could be due to a changing of the coordination number from 6 to 7 of Ca(2) polyhedron, which shares two edges with Ca(1) octahedron. According to [2], one of two potassium atoms in the unit cell is weakly linked and evidences some positional disorder not discussed by [2]. Structural refinement shows that K1 atom is distributed among at least three different positions having occupancy 0.658, 0.211 and 0.122, respectively. Similar behaviors were been observed also in tinaksite structure [4].

Recent studies on the synthesis, properties and structural characterization of some Ir complexes with arylpyridine ligands have attracted considerable interest in both academic and industrial fields due to their use as phosphorescent materials in light emitting diodes (PHOLEDs)[1]. One of the main advantages offered by this class of Ir complexes is the possibility to careful control their light emission colour by suitably choosing the kind and position of substituent groups[2]. Latest literature also shows that the stereochemistry of these complexes has a significant influence on their photophysical properties and performance in devices[3]. Therefore, structural studies of these materials are very important in order to identify univocally the atomic arrangement of the compounds under investigation. In a recent publication, we have synthesized and spectroscopically characterized a series of heteroleptic iridium complexes functionalized with benzylsulfonyl groups and fluorine atoms in different positions of 2-phenylpyridine ligands. Investigation of the stereochemistry of these complexes has been firstly carried out by 1H and 13C and NMR spectroscopy of their iridium dichloro-bridged dimer precursors. Here, we report the crystallographic characterization of the iridium dimers (PhSO2-F2ArPy)4Ir2Cl2 and (PhSO2-FArPy)4Ir2Cl2 which sheds light on their stereochemistry, as well as on the stereochemistry of the corresponding heteroleptic iridium complexes. The crystal structures were determined by SCXRD. Both complexes crystalize in P space group and have a trans configuration of the arylpyridine ligands. The geometry parameters and the atomic coordination around central Ir3+ ion are similar in both complexes, each one showing a regular octahedral arrangement of the donor atoms.

The structures of tokkoite, K2Ca4[Si7O18OH](OH,F) and tinaksite, K2Ca2NaTi[Si7O18OH]O from the Murun massif (Russia) were refined from single-crystal X-ray diffraction data in the triclinic space group P 1: Average crystallographic data are a≈10.423, b≈12.477, c≈7.112 Å, α≈89.92°, β≈99.68°, γ≈92.97°, V≈910.5 Å3 for tokkoite; a≈10.373, b≈12.176, c≈7.057 Å, α≈90.82°, β≈99.22°, γ≈ 92.80°, V≈878.5 Å3 for tinaksite. The substantial similarities between the geometrical parameters of the tokkoite and tinaksite structures led us to conclude that the two minerals are isostructural. However, major differences of tokkoite with respect to tinaksite are larger lattice constants, especially concerning the b parameter, longer <M–O> distances, especially <M1–O>; larger values of the M1–M3 and O20–O2 bond lengths, and a stronger distortion of the M1 polyhedron. Mössbauer analysis showed that significant trivalent iron is present, VIFe3+ 40.0(7)% in tokkoite and 12.8(3)% in tinaksite. It is confirmed that 2Ca2þ (M1þM2) +(F, OH)(O20) ↔ Ti4þ (M1) +Naþ(M2) +O(O20) is the exchange reaction that describes the relation between tokkoite and tinaksite. In addition, this exchange reaction causes local stress involving mainly the M1 site and its interaction with the M2 and M3 sites.

The control of pollutants emission from internal combustion engines is a worldwide issue, in the automotive field. The roadmap for the reduction of vehicle emission limits is driving the academic and industrial interest towards the development of innovative systems integrating novel detection elements and fast feedback circuits and actuators. Based on a tighter control over emissions, and starting from 2014, Euro 6 standards are expected to improve the environmental compatibility of a new generation of vehicles in Europe. This scenario calls for a significant improvement of the sensors technologies for the detection of the main pollutants related to the automotive field, including nitrogen oxides (NOx). In this work, we report on the synthesis and analytical characterization of hybrid nanocomposites containing gold nanoparticles (Au-NPs) and metal oxide nanostructures (MO-NPs, such as zirconium oxide, indium oxide, oxide mixtures, etc.). These species are promising for real-time detection of low levels of NOx species, owing to their low cost, high sensitivity and availability under a variety of stoichiometric and mixing ratios, showing different gas sensing characteristics [1- 2]. Different MO-NPs and mixed MO-NP systems were prepared using a simple but efficient sol-gel method. Subsequently, the nano-oxides were electrodecorated by Au-NPs. Since Au nanophases exhibit pronounced selectivity toward NOx gases [3], the resulting hybrid nanocomposites are expected to improve the nanomaterial sensing performance. All the nanomaterials were characterized using FTIR, XPS, XRD, TEM, and SEM techniques. Experimental evidences support further application of these NPs as active elements in novel NOx sensors.

A general method to synthesize conjugated molecules with a benzofulvene core is reported. Up to four conjugated substituents have been introduced via a three-step sequence including (1) synthesis of 1,2-bis(arylethynyl)- benzenes; (2) exo-dig electrophilic cyclization promoted by iodine; and (3) cross-coupling reaction of the resulting bisiodobenzofulvenes with organoboron, organotin, or ethynyl derivatives under Pd catalysis. Structural aspects of the new compounds are discussed.

The title complex, [Ir2(C18H13FNO2S)4Cl2]C7H8, was crystallized from dichloromethane solution under a toluene atmosphere. It is a dimeric complex in which each of the two IrII centres is octahedrally coordinated by two bridging chloride ligands and by two chelating cyclometallated 2-(5-benzylsulfonyl)- 3-fluoro-2-(pyridin-2-yl)phenyl ligands. The crystal structure analysis unequivocally establishes the trans disposition of the two cyclometallated ligands bound to each IrII centre, contrary to our previous hypothesis of a cis disposition. The latter was based on the 1H NMR spectra of a series of dimeric benzylsulfonyl-functionalized dichloride-bridged iridium complexes, including the compound described in the present work [Ragni et al. (2009). Chem. Eur. J. 15, 136–148]. The toluene solvent molecules, embedded in cavities in the crystal structure, are highly disordered and could not be modelled successfully; their contribution was removed from the refinement using the SQUEEZE routine in the program PLATON [Spek (2009). Acta Cryst. D65, 148–155].

The determination of the oxidation state and structural role of transition metals in minerals is a crucial challenge. XPS has proven to have a great potential in probing the site distribution and chemical states of Fe and Ti transition elements, provided that the right method to process the spectra is used. XPS spectra of these elements have the 2p core level region usually rich of features but the choice of the method for background removing can seriously affect the results of the quantitative analysis. Single crystals of brookite (TiO2) and natural micas (phlogopites) are investigated to examine the ef- fect of background subtraction on Ti2p and Fe2p signals. The backgrounds used are: (1) the “Linear” background; (2) the traditional “Shirley” background; (3) three different Tougaard-like backgrounds; and (4) the more recent “shape parameter, κ” method. In the case of the studied natural micas, the Fe chemical state proportion (Fe2+/Fetot) obtained with the corrected spectra varies by 10%. It is shown that TiO2 oxides are not suitable as standard for octahedral Ti4+ signal in the studied micas. The “shape parameter, κ” method proves to provide supplementary information useful for a full interpretation of XPS signals.

A wide range of teaching strategies have been employed to improve the effectiveness of STEM education. In some studies, music has been used as a tool to help memorizing scientific concepts. However, music (without lyrics) can also be considered in itself as an interesting way to explore and explain the complexity of both natural and artificial structures, and a way to guide learners of every age towards the deep understanding of the difficult concept of molecular order. For this purpose, we developed a scientifically based "decryption" method to assign a given sound to single atoms within crystals. All sound parameters (pitch, duration, timbre, and dynamics) are based on physical and chemical properties of the atoms involved in the structure. The "crystal soundtrack" is accompanied by animations highlighting the position of each atom considered in its context. Possible applications of this novel educational approach range from chemistry (atomic structures, the periodic table, the octet rule), to Earth sciences (the structure of natural crystals), material sciences (artificial structures), and biology (macromolecules such as sugars and nucleic acids). Musical examples will be presented and discussed.

A full characterisation of micas requires complete chemical analysis, including the determination of light elements, combined with Mössbauer spectroscopy or any technique suitable for the determination of ferric and ferrous iron contents, and crystal structural analysis (SCXRD). In this context, the SIMS technique is essential for a deeper understanding of the crystal chemistry of mica owing to its capability of precise and accurate quantification of light elements, i.e., H, Li, B, F, .... The role of SIMS is here outlined in the investigation of the complex crystal structure of mica, with new data on a set of volcanic samples, and their comparison with those from literature on trioctahedral micas from volcanic areas of Southern Italy. The importance of SIMS micro-spot (in-situ) analysis is here emphasized as a modern approach to gain insight into physico-chemical processes that affect grain-to-grain or intra-grain chemical variability in complex mineral structures.

A suite of Ti-bearing garnets from magmatic, metamorphic and carbonatitic rocks was studied by Electron Probe Microanalysis (EPMA), X-ray Powder Diffraction (XRPD), Single Crystal X-ray Diffraction (SCXRD), Mössbauer spectroscopy and Secondary Ion Mass Spectrometry (SIMS) in order to better characterize their crystal chemistry. The studied garnets show TiO2 varying in the ranges 4.9(1)-17.1(2) wt.% and variable Fe3+/ΣFe content. SIMS analyses allowed quantification of light elements yielding H2O in the range 0.091(7)-0.46(4), F in the range 0.004(1)-0.040(4) and Li2O in the range 0.0038(2)-0.014(2) wt%. Mössbauer analysis provided spectra with different complexity, which could be fitted to a number of components variable from one (YFe3+) to four (YFe2+, ZFe2+, YFe3+, ZFe3+). A good correlation was found between the Fe3+/ΣFe resulting from the Mössbauer analysis and that derived from the Flank method (Höfer & Brey, 2007). X-ray powder analysis revealed that the studied samples are a mixture of different garnet phases with very close cubic unit cell parameters as recently found by other authors (Antao, 2013). Single crystal X-ray refinements using anisotropic displacement parameters were performed in the Ia-3d space group and converged to R1 in the range 1.63-2.06 % and wR2 in the range 1.44-2.21 %. Unit cell parameters vary between 12.0641(1) and 12.1447(1) Å, reflecting different Ti contents and extent of substitutions at tetrahedral site. The main substitution mechanisms affecting the studied garnets are: YR4+ + ZR3+ ↔ ZSi + YR3+ (schorlomite substitution); YR2+ + ZR4+ ↔ 2YR3+ (morimotoite substitution); YFe3+↔ YR3+ (andradite substitution) with ZR4+ = Ti; YR4+ = Ti, Zr; YR3+ = Fe3+, Al3+, Cr3+; ZR3+ = Fe3+, Al3+ and YR2+ = Fe2+, Mg2+, Mn2+. The 2YTi4++ ZFe2+ ↔ 2YFe3+ + ZSi4+, the hydrogarnet substitution [(SiO4)4-↔ (O4H4)4-], the F– ↔ OH– and the YR4+ + XR+ ↔ YR3+ + XCa2+, with YR4+ = Ti, Zr; YR3+ = Fe3+, Al3+, Cr3+; XR+ = Na, Li also occur. The garnet crystal chemistry and implications in terms of nomenclature and classification (Grew et al., 2013) are discussed. Antao S.M. 2013. The mystery of birefringent garnet: is the symmetry lower than cubic?. Powder diffr., 28(4), 281-287. Grew E.S., Locock A.J., Mills S.J., Galuskina I.O., Galuskina E.V. & Hålenius U. 2013. Nomenclature of the Garnet Supergroup. Am. Mineral., 98, 785-811. Höfer H.E. & Brey G.P. 2007. The iron oxidation state of garnet by electron microprobe: Its determination with the flank method combined with major-element analysis. Am. Mineral., 92, 873-885.

The crystal structures of tobelite and NH4+-rich muscovite from the sedimentary rocks of the Armorican sandstones (Brittany, France) have been solved for the first time by single crystal X-ray diffraction. The structural study was integrated by electron probe microanalyses, X-ray photoelectron and micro-Fourier transform infrared spectroscopy. The crystals belong to the 2M2 polytype with the following unit-cell parameters: a = 9.024(1), b = 5.2055(6), c = 20.825(3) Å and β = 99.995(8) for tobelite and a = 9.027(1), b = 5.1999(5), c = 20.616(3) Å and β = 100.113(8)° for NH4+-rich muscovite. Structure refinements in the space group C2/c converged at R1 = 8.01%, wR2 = 8.84% and R1 = 5.59%, wR2 = 5.63% for tobelite and NH4+-rich muscovite, respectively. X-ray photoelectron spectroscopy revealed nitrogen environments associated either to inorganic (B.E. 401.31 eV) and to organic (B.E. 398.67 eV) compounds. Infrared spectra showed, in the OH- stretching region (3700-3575 cm-1), two prominent bands, centered at ~ 3629 and ~ 3646 cm-1, and two shoulders at ~ 3664 and ~ 3615 cm-1 which were assigned to Al3+Al3+-OH- arrangements having OH- groups affected by different local configurations. In addition, a series of overlapping bands from about 3500 to 2700 cm-1 characteristic of the NH4+-stretching vibrations, a main band at ~ 1430 and a shoulder at ~ 1460 cm-1 which were associated to the NH4+ bending vibration (ν4) were also present. The ammonium concentration was semi-quantitatively estimated in both crystals from the absorbance of the OH--stretching and NH4+-bending vibrations in the infrared spectra. Additional estimate was obtained for the NH4+-rich muscovite by considering the normalized peak area between K2p3/2 and N1s in the X-ray photoelectron spectrum. The obtained values were also in agreement with those derived from the interlayer spacing in the simulated X-ray powder diffraction spectra. The results of this integrated approach converged to (K0.18Na0.01NH4+0.62)Σ=0.81 (Al1.98Fe2+0.02)Σ= 2.00(Si3.19Al0.81)Σ= 4.00O10.00OH2.00 for tobelite and to (K0.46Na0.03Ba0.01NH4+0.36)Σ=0.86 (Al1.98Mg0.01Fe2+0.01V3+0.01)Σ=2.01(Si3.13Al0.87)Σ=4.00O10.00F0.08OH1.92 for NH4+-rich muscovite.

Two mineral clays of the montmorillonite group were tested as sorbents for the removal of Rare Earths (REs) from liquid solutions. Lanthanum and neodymium model solutions were used to perform uptake tests in order to: (a) verify the clays sorption capability, (b) investigate the sorption mechanisms and (c) optimize the experimental parameters, such as contact time and pH. The desorption was also studied, in order to evaluate the feasibility of REs recovery from waters. The adsorption–desorption procedure with the optimized parameters was also tested on a leaching solution obtained by dissolution of a dismantled NdFeB magnet of a hard-disk. The clays were fully characterized after REs adsorption and desorption by means of X-ray powder diffraction (XRPD) and X-ray photoelectron spectroscopy (XPS); the liquid phase was characterized via Inductively Coupled Plasma–Optical Emission Spectroscopy (ICP–OES) analyses. The experimental results show that both clays are able to capture and release La and Nd ions, with an ion exchange mechanism. The best total efficiency (capture 50%, release 70%) is obtained when the uptake and release processes are performed at pH = 5 and pH = 1 respectively; in real leached scrap solutions, the uptake is around 40% but release efficiency is strongly decreased passing from a mono-ion system to a real system (from 80% to 5%). Furthermore, a strong matrix effect is found, with the matrix largely affecting both the uptake and the release of neodymium.

This study reports a petrographic and crystal chemical analysis of three types of micas (yangzhumingite, light brown phlogopite and dark brown phlogopite) found in a lamproitic dyke at the Kvaløya Island (North Norway). The study was carried out integrating different analytical techniques: electron microprobe, single crystal X-ray diffraction, inductively coupled plasma mass spectrometry, Mössbauer and micro-Fourier Transform infrared spectroscopy. Kvaløya yangzhumingite (second occurrence in nature) was characterized for the first time in detail via single crystal X-ray diffraction. The different mica types are distinguishable on the basis of the VIFe and Mg versus Si content. Yangzhumingite composition is intermediate between those of KMg2.75(Si3.5Al0.5)O10F2 and KMg2.50Si4O10F2 synthetic compounds reported in the literature. Light and possibly dark brown phlogopite is a Mg-rich fluorotetraferriphlogopite, the latter having a greater Fe content. The infrared spectra of yangzhumingite and the light brown phlogopite show the occurrence of OH- absorption bands respectively at: ~ 3586 cm- 1 which correlates well with the measured F content; 3707 cm- 1 and 3686 cm- 1 assigned mainly to 3Mg2 +-K+-OH- (phlogopitic) environment. Structural analyses, performed only on yangzhumingite and light brown phlogopite show that both samples are 1M polytypes with the expected space group C2/m. Crystal chemical details are compatible with the following major substitution mechanisms: 2XIIK+ + VI[] ↔ 2XII[] + VIR2 + (where R2 + = Mg, Fe), OH- ↔ F- for yangzhumingite and 2VIR2 + ↔ VITi4 + + VI[] (Ti-vacancy), OH- ↔ F- for light brown phlogopite. All three types of micas formed at relatively constant low pressure, but over a large temperature range in equilibrium with a grain boundary fluid that underwent significant changes in composition during reaction progress. Light brown phlogopite cores and dark brown phlogopite rims formed during crystallization from the lamproitic magma, while yangzhumingite formed as a result of reactions between the already formed phlogopite and the highly reactive fluid that was derived from the volatile-rich lamproite magma.